Comparison of single and double detection points Taylor Dispersion Analysis for monodisperse and polydisperse samples

The purpose of this work was to compare single and double detection points Taylor Dispersion Analysis (TDA) of monodisperse and polydisperse samples for low injected volumes. For that, the hydrodynamic radii of human and bovine serum albumins, a poly(styrene sulfonate) standard and two dendrigraft poly-L-lysines were determined by TDA on a capillary electrophoresis instrument using a modified detection interface allowing the analysis on two detection points. The results were compared to values obtained via a single detection point TDA with adequate corrections for the finite injected volume. The results showed no significant difference between the double and single detection points when Taylor conditions were respected and when the injected volume was less than 1% of the capillary volume till the detection window. The issue of the determination of the peak variance of the Taylorgram in the case of polydisperse sample with non-Gaussian peak is addressed. A criterion is proposed to define the interval of time on which the peak variance is calculated by integration as a function of the signal to noise ratio.